Process and device for reducing the inrush current when powering aninductive load
AssigneeFraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
InventorMichael Konstanzer
Life of this patent
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Abstract
A transformer is energized from an a.c. source by initially applying the . voltage to the transformer during small but progressively increasing fractions of a succession of initial half-cycles. This is continued until the rated voltage is achieved or until the reactive current exceeds a predetermined value below that which would cause tripping of the transformer. In the event that the reactive current reaches the predetermined value, the remanence of the transformer is set at a selected level by applying the a.c. voltage to the transformer during an additional half-cycle. The length of exposure of the transformer to the a.c. voltage during the additional half-cycle depends upon the circumstances. Once the remanence has been set, operation of the transformer proceeds normally.
Claims85
A method of energizing an electrical load with a cyclical voltage, comprising the steps of:
- sensing a selected current component of the load produced by the supply of said cyclical voltage;
- initiating supply of voltage to said load, while performing the sensing step, for a fraction of at least one selected part-cycle of each of a plurality of successive voltage cycles, the fraction of the part cycle of the successive voltage cycles increasing progressively during the initiating step, maintaining the initiating step until one of the fractional selected part-cycles causes said selected load current component to reach a predetermined current magnitude or until the voltage applied to said load reaches a predetermined voltage magnitude;
- and
- continuing to supply said load with voltage following the initiating step with additional part-cycles of said cyclical voltage.
A circuit for energizing an electrical load having a magnetizable core, from a source of cyclical voltage, comprising:
- means for sensing a selected current component of the load produced by the supply of the cyclical voltage;
- and
- means connected to said sensing means for regulating the voltage supplied to the load, said regulating means including activating means for:
- (i) initiating the supply of voltage to the load to subject the load to the cyclical voltage for progressively increasing fractions of selected voltage part-cycles until one of the fractional selected part-cycles causes the selected current component to reach a predetermined current magnitude or until the voltage applied to the load reaches a predetermined voltage magnitude, and
- (ii) thereafter continuing to supply to the load the cyclical voltage during additional voltage part-cycles.
Dependencies are inferred from the claim text.